Electric dry cells

ABSTRACT

AN ELECTRIC DRY CELL HAVING THE OPEN END OF ITS CUP ELECTRODE CLOSED BY A MOULDED PLASTICS PLUG WHICH IS GRIPPED AROUND ITS PERIPHERY BY THE INTURNED END OF THE CUP AND HAS A CENTRAL APERTURE EMBRACING THE ROD ELECTRODE, ANNULAR SPACES FILLED WITH SEALING MATERIAL BEING PROVIDED RESPECTIVELY BETWEEN THE PERIPHERY OF THE PLUG AND THE WALL OF THE CUP ELECTRODE, AND BETWEEN THE ROD ELECTRODE AND THE WALL OF THE CENTRAL APERTURE IN THE PLUG.

/N VEN TORS CHI/VG 'Koo/v PUN BY Cfu/v6-F C/mu Poo/v dem; 1%4/ HTT'OR/VE YS ELECTRIC DRY" CELLS Filed July 16, 1969 CHING-KOON PUN ETALNov. so, 19'7-1 United States Patent O 3,623,915 ELECTRIC DRY CELLSChing-Kaon Pun and Ching-Chau Poon, both of P.0. Box 5538, Kowloon, HongKong Filed July 16, 1969, Ser. No. 842,274 Claims priority, applicationGreat Britain, July 11, 1969, 35,369/ 69 Int. Cl. H01m 1 02 U.S. Cl.136--133 7 Claims ABSTRACT F THE DISCLOSURE An electric dry cell havingthe open end of its cup electrode closed by a moulded plastics plugwhich is gripped around its periphery by the inturned end of the cup andhas a central aperture embracing the rod electrode, annular spaces lledwith sealing material being provided respectively between the peripheryof the plug and the wall of the cup electrode, and between the rodelectrode and the wall of the central aperture in the plug.

This invention relates to electric dry cells of the kind which includean outer cup-like electrode or can and an inner rod-shaped electrodepositioned centrally and coaxially of the cup electrode, which cells arethose hereinafter referred to as being of the kind described. Theinvention is particularly directed to improvements in the sealingarrangements at the mouth of the cup electrode or can, where a plug isnormally provided whose primary purposes are to close the open end ofthe cup and to maintain the rod electrode in its desired positioncentrally of the cup.

According to the invention there is provided an electric dry cell of thekind described, having a plug made of electrically insulating plasticsmaterial mounted in the open end of the cup electrode to seal such openend, said plug being gripped around its periphery by the inturned rim ofthe cup electrode and having a central aperture whose wall embraces theouter end region of the rod electrode, a first afnnular enclosed spacebeing provided between a peripheral face of the plug and the insidesurface of the inturned rim of the cup electrode, and a second annularenclosed space being provided between a face of the central aperture ofthe plug and the wall of the rod electrode, both of such spaces beingfilled with sealing material.

Such arrangement provides a much more efficient seal between the plugand the electrodes than is the case in conventional cells in which theinturned rim of the cup surrounds the periphery of the plug, and theplug surrounds the rod electrode, without the interposition of anysealing material. The cup electrode may still of course be provided witha conventional outer insulating sheath of cardboard or plastics materialand with a further outer metal casing if desired. The sealing materialmay be of any convenient kind such as wax, asphalt, liquid asphalt,monolithium chloride and resin, adhesive material or the like.

[Preferably the said peripheral face of the plug is formed with anannular face portion extending obliquely to the longitudinal axis of thecell and defining the inner wall of the said first annular enclosedspace. The said annular face portion of the peripheral face of the plugis preferably of outwardly concave configuration.

'Preferably the said face of the central aperture of the plug is formedwith an annular face portion extending obliquely to the longitudinalaxis of the cell and defining the outer wall of the said second annularenclosed space.

The said second annular enclosed space may conveniently be partlydefined by the underneath face of a contact cap 'mounted on the outerend of the rod electrode. The said contact cap may be of the kind whichdoes not extend radially outwardly from the rod electrode to any greatextent, in which case the said plug will also constitute the end closureof the cell, or the contact cap may extend outwardly as far as theperiphery of the plug and thus itself provide such end closure; in thelatter case the periphery of the contact cap may be connected in knownfashion to (but of course insulated from) the rim of the cup electrode.

Preferably an annular groove or slot is provided in the outer surface ofthe plug near to its periphery for the reception of the inwardly turnedrim of the cup. If the cup is provided with an outer metal sheath thelast mentioned groove or slot may be enlarged for the reception of theinturned rim of such sheath.

The plug may conveniently be of internally domed configuration toprovide more space for the contents of the cell, whilst its centralaperture may be defined by an elongate sleeve embracing the rodelectrode. Preferably the inner end of the said sleeve engages the outerend face of a depolarizer dolly of the cell, or an end cover plate ofsaid dolly, and the said inner end of the sleeve is formed with arnumber of circumferentially spaced cut-outs for air circulation withinthe cell.

In order that the invention may be more readily understood oneembodiment of the same, together with a modification thereof, will nowbe described by way of example and Iwith reference to the accompanyingdrawings, in which:

|FIG. 1 is an axial cross-sectional view of an electric dry cellaccording to the invention;

|FIG. 2 is a similar view of the top part of the cell of FIG. 1, but toan enlarged scale; and

FIG. 3 is a View similar to that of FIG. 2 but showing a modification.

This embodiment of an electric dry cell according to the inventioncomprises an outer cup electrode in the form of a cylindrical open-endedvzinc can 1, and an inner rod electrode 2 made of carbon and positionedcentrally and coaxially of the cup electrode.

The major part of the annular space between the rod electrode 2 and thecup electrode 1 is filled by a conventional depolarizer dolly 3, theannular gap between the outside surface of such dolly and the insidewall of the cup electrode being filled with electrolytic paste 4; thedolly 3 is preferably supported and located centrally and coaxially ofthe cup electrode, and thus held spaced from the wall of the can, by acup-like spacing element 5 as described and claimed in our co-pendingU.S. Application, Ser. No. 842,119, filed July 16, 1969. A base plate 6forming part of the spacing element 5, or some other separate and knownelement, is provided to insulate the lower end of the rod electrode 2and the underside of the dolly 3 from the floor of the cup electrode 1.

The open end of the cup electrode 1 is closed by a plug 7 formed ofelectrically insulating plastics material, such plug being of annularform with its central aperture surrounding and gripping the top endregion of the rod electrode whilst its peripheral region is gripped bythe inturned rim of the cup electrode.

Referring now particularly to FIG. 2 the central aper ture in the plugis dened by a sleeve 8 which depends from a generally flat body portion9 of the plug, whilst at its periphery the plug is formed with adependent annular skirt 10 so that the plug as a whole is of generallyhollow configuration. A number of radial strengthening webs 11 extendbetween the central sleeve 8 of the plug and its peripheral skirt 10.

The plug 7 is formed at its periphery, around the upper and outer regionof its skirt 10, with a somewhat concave oblique face 12 which facesupwardly and outwardly towards the inner wall of the inturned rim of thecup electrode 1. An annular space is thus defined between such obliqueface 12 and the inner wall of the cup, and before the rim of the cup isspun into engagement with the plug this space is filled with a sealingmaterial 13 such as wax, asphalt, liquid asphalt, monolithium chlorideand resin, adhesive material or the like.

A further but inwardly and upwardly facing oblique face 14 is formed atthe inner and upper region of the central sleeve 8 of the plug 7. Thetop end of the rod electrode 2, which the sleeve 8 surrounds, isprovided with a metal contact cap 15 having an outwardly extendingannular ange portion 16. An annular space is thus defined between theunderneath surface of the flange 16, the wall of the rod electrode 2 andthe annular oblique face 14 of the plug sleeve 8. Before the contact cap15 is mounted on the rod electrode '2 such space is filled with sealingmaterial 17 similar to that used at the periphery of the plug.

The lower end of the sleeve 8 of the plug 7 rests on a top cover plate21 of the depolarizing dolly 3, and is formed with a number ofcircumferentially spaced cutouts 22 to increase air circulation withinthe cell. The dolly cover plate 21 serves to bring about an eventransmission of pressure from the inturned rim of the cup electrode 1 tothe dolly 3 via the webs 11 of the plug 7.

The contact cap 1S on the rod electrode 2 may if desired extendoutwardly to the periphery of the plug 7 so as to form and end closureof the cell. The edge of the cap may then be incorporated into the sealbetween the plug and the rim of the cup electrode 1, whilst of coursebeing insulated from the latter. Such insulation may be achieved inknown manner by mounting a ring of insulating plastics or rubbermaterial around the edge of the contact cap before the rim of the cupelectrode is spun over. Alternatively, the end region of an insulatingsheath provided on the cup electrode can be arranged to engage betweenthe rim of the cup and the edge of the contact cap.

The rim of the cup electrode 1 is spun over into engagement with the topsurface of the plug 7 and is received in an annular groove 18 formed insuch plug surface near to its periphery. FIG. 3 shows a modification inwhich the cup electrode is provided with an insulating sheath 19 ofcardboard or plastics materials and an outer tubular metal casing 20,and in this embodiment the groove 18 is enlarged for the reception ofthe inturned ends of the insulating sheath and outer metal casing.

The sealing effect between the plug 7 and the electrodes 1 and 2 can befurther enhanced if, as in a preferred form of the invention, theoutside diameter of the plug is made slightly greater than the insidediameter of the cup, whilst the diameter of the central aperture in theplug is made slightly smaller than the outside diameter of the rodelectrode, so that a very tight engagement is provided between suchparts; to achieve such engagement the plug will be formed of a somewhatresilient plastics material. Further, a thin layer of coagulatingadhesive material may be provided between the periphery of the plug andthe cup electrode and between the inside of the plug and the rodelectrode so as to enhance the seal still further.

In another modification, which is not illustrated, thev conventionallongitudinal seam in the outer metal casing may be omitted, and spacethus saved therewithin, by

4 spinning the bottom end of such casing over a metal or plastics ringwhich will serve to hold the casing in its cylindrical shape. The bottomcorner of the cup electrode may then be formed with a shallow annularindentation for the reception of the ring.

It will thus be seen that the invention provides a dry cell in which theseal between the plug for the mouth of the cell and the electrodesthereof is substantially improved as compared with known arrangements.

We claim:

1. An electric dry cell comprising an outer cup-like electrode, an innerrod-shaped electrode positioned centrally of the cup electrode, and acentrally apertured plug made of electrically insulating plasticsmaterial mounted in the open end of the cup electrode and sealinglyassociated with the respective electrodes, the rim of the cup electrodebeing turned inwardly over the edge of the plug, characterized in thatthe seal between the plug and the cup electrode is provided by anoutwardly opening annular channel between the outer peripheral face ofthe plug and the inside wall of the cup electrode adjacent the rim ofthe latter, said channel being filled with sealing material, the sealbetween the plug and the rod electrode being provided by an outwardlyopening annular channel on the inner peripheral face of the plug betweenthe plug face and the surface of the rod electrode, said channel being`filled with sealing material, and a flanged contact cap on the end ofthe rod electrode, enclosing the said channel.

2. A cell as claimed in claim 1, wherein the outer peripheral face ofthe plug is formed with an annular face obliquely to the longitudinalaxis of the cell, to define one wall of the said annular channel betweenthe plug and the cup electrode.

3. A cell as claimed in claim 1, wherein the inner peripheral face ofthe plug is formed with a part-conical portion to define one wall of thesaid annular channel between the plug and the rod electrode.

4. A cell as claimed in claim 1, wherein the said contact cap onlycovers the outer end of the rod electrode and the inner one of saidchannels, the said plug constituting the end closure of the cell.

S. A cell as claimed in claim 1, wherein an annular groove is providedin the outer surface of the plug near to its periphery receiving theinwardly turned rim of the cup.

6. A cell as claimed in claim S, wherein the cup electrode is providedwith an outer metal sheath whose inturned rim is also received in saidannular groove.

7. A cell as claimed in claim l, wherein the said plug is of internallydomed configuration.

References Cited UNITED STATES PATENTS 2,712,034 6/1955 Seavey et al.136-133 2,766,316 lO/1956 Stevens et al. 136-133 FOREIGN PATENTS 574,951l/l946 Great Britain 136-133 61,689 5/1955 France 136-133 (Firstaddition of 1,029,283)

DONALD L. WALTON, Primary Examiner U.S. Cl. X.Rv 136-169 UNTTED STATESPATENT OFFICE CERTIFICATE 0F CORRECTIN Patent No 3.623.915 Dated Nov- 3o1971 Ilfnvencods) CHING-KooN PUN et al y It is certified that errorappears in the above-identified patent and that said Letters Patent arehereby corrected as shown below:

Column l, line 7, "July ll, 1969" should read July 24, 1968 line 8,"35,369/69" should `read 35, 3569/68 Signed and sealed this 25th day ofApril 19Y2.

(SEAL Attest:

FEJDLJAPJD IYLFLETCEL-, JH. ROBERT GOTTSGHALK Attesting OfficerCommissioner o' Patents

